The routine analyses of coal as a fuel for any thermal system, and especially when used for power plants and steam generators, commonly involves laboratory evaluations of samples of the fuel, including: the fuel's elementary composition free of ash and water; the fuel's ash resultant from combustion; the fuel's water, and the fuel's heating value. The combined analyses of elementary composition, fuel ash and fuel water is herein defined as an ultimate analysis. These evaluations supply important data to users of coal, to operators of coal-fired power plants, and to the Input/Loss Method and its associated technologies. The Input/Loss Method and its associated technologies are described in the following United States patent applications and resulting patents: Ser. No. 09/273,711 which issued on Feb. 18, 2003 as U.S. Pat. No. 6,522,994 (hereinafter termed '711), Ser. No. 09/630,853 which issued on Jun. 24, 2003 as U.S. Pat. No. 6,584,429 (hereinafter termed '853), and Ser. No. 09/827,956 which issued on May 6, 2003 as U.S. Pat. No. 6,560,563 (hereinafter termed '956). A rudimentary Input/Loss Method is described in U.S. Pat. No. 5,367,470 issued Nov. 22, 1994 (hereinafter termed '470), and in U.S. Pat. No. 5,790,420 issued Aug. 4, 1998 (hereinafter termed '420).
A typical ultimate analysis, and as herein defined, produces the following quantities on a weight bases: carbon, hydrogen, oxygen, nitrogen, sulfur, ash resultant from combustion, and the fuel's water. Reported carbon is the total, from both organic and inorganic substances. Reported hydrogen is the total but without water's hydrogen. Reported oxygen is the total, from both organic and inorganic substances, but without water's oxygen. For reported ash, it is routine in laboratory analyses to simply weight the ash resultant after combustion of the sampled fuel; this is commonly assumed to be the fuel's mineral matter associated with the originating sample before combustion. For example, in '711 the present inventor, without the knowledge gained in developing this invention, states “By fuel ash is meant the fuel's non-combustible mineral content, before firing.”This assumption is generally valid for coals, as commonly its mineral matter contains metal oxides, other non-combustible materials and non-combustible rocks. If, for example, mineral carbonates are present in coal as CaCO3, which is typical, then solid CaO will result as a product of combustion to be found in the resultant ash, with production of gaseous CO2 given reduction of CaCO3. Thus CaO will be reported as a portion of the coal's ash. No distinction is made between CO2 produced from organic matter, i.e., from the coal's organic matrix, versus from mineral carbonates. No information on CO2 producing inorganic materials is routinely provided, nor routinely sought. Such CO2 producing inorganic materials include mineral carbonates found in certain coals, and typically includes CaCO3 and MgCO3. Free CO2 is also found in gaseous fuels, such as natural gas.
The Input/Loss Method described in '711 advocates determining elementary compositions of fossil fuels based on certain “operating parameters” principally including effluent measurements, and with that information to then determine the fuel's heating value and the system heat rate (note that heat rate is inversely related to system efficiency by the following: Heat Rate (Btu/kWh)=3412.1416/Efficiency). However, '711 offers no consideration as to the presence of CO2 producing mineral matter found in the fuel. The Input/Loss Method and its associated technologies is dependent on at least: 1) operating parameters which include effluent measurements; 2) establishing certain “reference fuel characteristics” for determining hydrogen versus carbon, and oxygen versus carbon relationships; 3) establishing historical reference fuel characteristics for determining the L Factor used by the Input/Loss Method to correct effluent measurements; 4) determining boiler efficiency by recognizing combustible and non-combustible materials within the fuel proper (i.e., its elementary composition, fuel water and fuel ash, apart from injected limestone or other added sorbents); and 5) determining a fuel's heating value based on understanding of the fuel's oxygen to carbon ratio, elementary composition and reference fuel characteristics. The fossil fuel's elementary composition and its reference fuel characteristics are important to any method which determines fuel chemistry, fuel heating value, and/or boiler a efficiency of a fossil fired thermal system in real-time via on-line monitoring. Fuel heating value and fuel flow (resulting in total fuel energy flow), and useful system output lead to a determination of system heat rate.
It has been found when developing this invention that between 1% to 5% CO2 production, per weight of As-Fired fuel, has been found in Powder River Basin coals (found in Wyoming and Montana). Such coals have also been found in Greece and China. In general, high CO2 production from mineral matter may be anticipated from coals whose analyzed ash has high CaO contents, suggestive of the presence of CaCO3 in the unburned fuel's mineral matter. In addition to Powder River Basin coals, this situation is common with many lignite coals. 1% CO2 by weight of the As-Fired fuel adversely effects Input/Loss computed fuel heating values by 3.55%. 1% CO2 by weight of the As-Fired fuel effects the oxygen to carbon ratio of coal by 9.5% on a weight base; the oxygen to carbon ratio is used for heating value predictions.
There is no known prior art for this invention. Eq.(29) found in '470, '420 and '711, describing a combustion equation, includes the quantity of gaseous CO2 found in the fuel's constituents; termed α7. Eq.(19) found in '853, describing a combustion equation, includes the quantity of CO2 found in the fuel's constituents; also termed α7. However, Patents '470 and '420 make no mention of any corrections nor otherwise address CO2 producing inorganic materials found in fossil fuels. Applications '711, '853 and '956 and their related provisional patent applications and Continuation-In-Parts, make no mention of any corrections nor otherwise address CO2 producing inorganic materials found in fossil fuels. Although the presence of limestone (CaCO3) and its inclusion in combustion stoichiometrics is taught in these applications, denoted by reference as “PLS” (i.e., Pure LimeStone), CO2 production from limestone is treated uniquely, apart from the fuel per se, as such limestone is injected separately into the combustion process for control of sulfur emissions; CO2 production from mineral matter found within the fuel is not mentioned.